December 2016 - ghc-tickets

[GHC] #12952: Broken tests: ghci014 maessen_hashtab qq006
by GHC 08 Dec '16

08 Dec '16

#12952: Broken tests: ghci014 maessen_hashtab qq006 -------------------------------------+------------------------------------- Reporter: Rufflewind | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Test Suite | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: ghci014 | Blocked By: maessen_hashtab qq006 | Blocking: | Related Tickets: Differential Rev(s): D2807 | Wiki Page: -------------------------------------+------------------------------------- {{{ ghci/scripts/ghci014.run ghci014 [bad stderr] (ghci) programs/maessen-hashtab/maessen_hashtab.run maessen_hashtab [exit code non-0] (hpc) quasiquotation/qq006/qq006.run qq006 [exit code 0] (normal) }}} The first two were fairly straightforward: `ghci014` and `maessen_hashtab` are broken because they rely on a very ancient version of QuickCheck. I don't know what is up with `qq006`. It doesn't compile on GHC 8.0.1 but now apparently it does on GHC HEAD. Is this a bug or a change in semantics? -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12952> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12388: Don't barf on failures in the RTS linker
by GHC 08 Dec '16

08 Dec '16

#12388: Don't barf on failures in the RTS linker -------------------------------------+------------------------------------- Reporter: dobenour | Owner: Type: bug | Status: new Priority: normal | Milestone: 8.2.1 Component: Runtime | Version: 8.0.1 System (Linker) | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- The RTS linker currently calls `barf()` when it fails. This is a problem because: 1. It appears that there is a bug in GHC, when there is no bug. 2. Failures to load code really should be recoverable. According to a `TODO` in the code, the culprit is resource deallocation, which is very difficult due to the code being written in C and having complicated control flow. There are a few solutions: - Port the RTS linker to C++ and use RAII for resource management. Failures would be handled (internally to the linker) by throwing a C++ exception. This is actually my favorite, but might not be popular with the GHC devs. - Build a huge context struct containing all needed resources and free it before returning. Signal errors with `longjmp()`. - Try to find each and every place where resources need to be free, and free them by hand. Signal errors with return codes. This seems too error-prone. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12388> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12945: Backpack signature matching doesn't pick up orphan instances
by GHC 08 Dec '16

08 Dec '16

#12945: Backpack signature matching doesn't pick up orphan instances -------------------------------------+------------------------------------- Reporter: ezyang | Owner: ezyang Type: bug | Status: new Priority: high | Milestone: 8.2.1 Component: Compiler | Version: 8.1 (Type checker) | Keywords: backpack | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Repro: {{{ unit impl where module A where data T = T module B(module A, module B) where import A instance Show T where show T = "T" unit sig where signature B where data T = T instance Show T module App where import B app = print T unit main where dependency sig[B=impl:B] module Main where import App main = app }}} I get: {{{ ezyang@sabre:~$ ghc-head --backpack foo.bkp [1 of 3] Processing impl Instantiating impl [1 of 2] Compiling A (.hs -> .o) [2 of 2] Compiling B (.hs -> .o) [2 of 3] Processing sig [3 of 3] Processing main Instantiating main [1 of 1] Including sig[B=impl:B] Instantiating sig[B=impl:B] [1 of 2] Compiling B[sig] (.hsig -> .o) sig/sig-HVnmSw44WZeBfwnUur4wzl/../B.hi:1:1: error: No instance for (GHC.Show.Show impl:A.T) arising when attempting to show that instance [safe] GHC.Show.Show impl:A.T -- Defined in ‘impl:B’ is provided by ‘impl:B’ }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12945> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #1791: heap overflow should generate an exception
by GHC 08 Dec '16

08 Dec '16

#1791: heap overflow should generate an exception -------------------------------------+------------------------------------- Reporter: guest | Owner: Type: feature request | Status: patch Priority: normal | Milestone: ⊥ Component: Runtime System | Version: 6.8 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: outofmem2 Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D2790 Wiki Page: | -------------------------------------+------------------------------------- Changes (by bgamari): * status: new => patch * differential: => Phab:D2790 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/1791#comment:16> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4505: Segmentation fault on long input (list of pairs)
by GHC 08 Dec '16

08 Dec '16

#4505: Segmentation fault on long input (list of pairs) -------------------------------------+------------------------------------- Reporter: cathper | Owner: Type: bug | Status: new Priority: high | Milestone: 8.0.2 Component: Compiler | Version: 7.0.1 Resolution: | Keywords: Segmentation | fault, segfault, long input Operating System: Linux | Architecture: x86_64 | (amd64) Type of failure: Runtime crash | Test Case: Blocked By: 4258 | Blocking: Related Tickets: | Differential Rev(s): Phab:D1180 Wiki Page: | -------------------------------------+------------------------------------- Changes (by bgamari): * status: patch => new -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4505#comment:47> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4505: Segmentation fault on long input (list of pairs)
by GHC 08 Dec '16

08 Dec '16

#4505: Segmentation fault on long input (list of pairs) -------------------------------------+------------------------------------- Reporter: cathper | Owner: Type: bug | Status: patch Priority: high | Milestone: 8.0.2 Component: Compiler | Version: 7.0.1 Resolution: | Keywords: Segmentation | fault, segfault, long input Operating System: Linux | Architecture: x86_64 | (amd64) Type of failure: Runtime crash | Test Case: Blocked By: 4258 | Blocking: Related Tickets: | Differential Rev(s): Phab:D1180 Wiki Page: | -------------------------------------+------------------------------------- Comment (by bgamari): Please ignore comment:45 which was intended for #229. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4505#comment:46> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4505: Segmentation fault on long input (list of pairs)
by GHC 08 Dec '16

08 Dec '16

#4505: Segmentation fault on long input (list of pairs) -------------------------------------+------------------------------------- Reporter: cathper | Owner: Type: bug | Status: patch Priority: high | Milestone: 8.0.2 Component: Compiler | Version: 7.0.1 Resolution: | Keywords: Segmentation | fault, segfault, long input Operating System: Linux | Architecture: x86_64 | (amd64) Type of failure: Runtime crash | Test Case: Blocked By: 4258 | Blocking: Related Tickets: | Differential Rev(s): Phab:D1180 Wiki Page: | -------------------------------------+------------------------------------- Changes (by bgamari): * status: new => patch Comment: Here is a quick attempt at a patch: https://github.com/bgamari/array/commit/73144bda5cf4f5ba2e73206ea0a53200e30…. The only trouble here is that we now are doing overflow in unsafe indexing operations, which will cost a bit of performance. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4505#comment:45> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12941: Extend nofib with benchmarks focused on compiler performance
by GHC 08 Dec '16

08 Dec '16

#12941: Extend nofib with benchmarks focused on compiler performance -------------------------------------+------------------------------------- Reporter: michalt | Owner: michalt Type: task | Status: new Priority: normal | Milestone: 8.4.1 Component: NoFib | Version: benchmark suite | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- GHC seems to be missing a set of benchmarks focused on the compiler performance that would contain some realistic examples and make it easy to test even small changes in the compiler (by having a simple "before and after" comparison). The two main use cases would be: - Anyone hacking on GHC could quickly check even for small performance differences (running the benchmark with and without their change). - Tracking performance of GHC over time (potentially as part of perf.haskell.org) We already have two collections of performance tests/benchmarks: - `tests/perf/compiler` which contains actual tests (part of `validate`) and seems to be focused on larger regressions (if the bounds are too tight, it can generate a fair amount of noise). - `nofib` which is mostly focused on benchmarking the code produced by GHC (the vast majority of the modules compile within 400ms). The current idea is to extend `nofib` with some modules that are only checking the performance of GHC (e.g., might be a library module that doesn't contain `main`). Please see: https://mail.haskell.org/pipermail/ghc- devs/2016-December/013323.html for an initial discussion about this. Also related: - Ticket focused on improvements to `tests/perf/compiler` #12758 - Proposal of having a similar tests but hosted in a separate repo on github: https://github.com/ghc-proposals/ghc-proposals/pull/26 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12941> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #1311: newtypes of unboxed types disallowed - documentation bug and/or feature request
by GHC 07 Dec '16

07 Dec '16

#1311: newtypes of unboxed types disallowed - documentation bug and/or feature request -------------------------------------+------------------------------------- Reporter: Isaac Dupree | Owner: osa1 Type: feature request | Status: new Priority: low | Milestone: ⊥ Component: Compiler | Version: 7.7 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by RyanGlScott): * cc: RyanGlScott (added) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/1311#comment:16> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #7289: Mingw FPU init not Windows compatible.
by GHC 07 Dec '16

07 Dec '16

#7289: Mingw FPU init not Windows compatible. -----------------------------------+-------------------------------- Reporter: Lennart | Owner: Phyx- Type: bug | Status: upstream Priority: normal | Milestone: 8.2.1 Component: Runtime System | Version: 7.2.2 Resolution: | Keywords: Operating System: Windows | Architecture: x86 Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -----------------------------------+-------------------------------- Changes (by Phyx-): * owner: => Phyx- Comment: Sure, I'll whip up a patch in the weekend. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7289#comment:10> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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